I've just noticed that
gfix -sweep alias
when executed in the bin directory sometimes returns 'unavailable database'
if I stop and restart the fb service, I get a silent exit from the command.

but I'd like to know what causes unavailable database.
it's supposed to run without exclusive access.

and why does stopping and restarting the service do to make it work again.
There are no validation errors in the database.

 regards
 Alan McDonald